This vast county stretches from where the bulk of the county population resides in two Census County Divisions, holding 1,422,745 people as of the 2010 Census, covering the 450 square miles (1,166 km2), across the thinly populated deserts and mountains. It spans an area from south of the San Bernardino Mountains in San Bernardino Valley, to the Nevada border and the Colorado River.

The bulk of the population, roughly two million, live in the roughly 480 square miles south of the San Bernardino Mountains adjacent to Riverside and in the San Bernardino Valley. Over 300,000 others live just north of the San Bernardino Mountains, agglomerating around Victorville covering roughly 280 square miles in Victor Valley, adjacent to Los Angeles County. Roughly another 100,000 people live scattered across the rest of the sprawling county.

There are at least 35 official wilderness areas in the county that are part of the National Wilderness Preservation System. This is the largest number of any county in the United States (although not the largest in total area). The majority are managed by the Bureau of Land Management, but some are integral components of the above listed national protected areas. Most of these wilderness areas lie entirely within the county, but a few are shared with neighboring counties (and two of these are shared with the neighboring states of Arizona and Nevada).

Except as noted, these wilderness areas are managed solely by the Bureau of Land Management and lie entirely within San Bernardino County:

There were 528,594 households, out of which 43.7% had children under the age of 18 living with them, 55.8% were married couples living together, 14.8% had a female householder with no husband present, and 23.5% were non-families. 18.4% of all households were made up of individuals, and 6.6% had someone 65 years of age or older living alone. The average household size was 3.2 people, and the average family size was 3.6 people.

The number of homeless in San Bernardino County grew from 5,270 in 2002 to 7,331 in 2007, a 39% increase.[24]

In the county, the population was spread out—with 32.3% under the age of 18, 10.3% from 18 to 24, 30.2% from 25 to 44, 18.7% from 45 to 64, and 8.6% who were 65 years of age or older. The median age was 30 years. For every 100 females, there were 99.6 males. For every 100 females age 18 and over, there were 97.2 males.

The median income for a household in the county was $42,066, and the median income for a family was $46,574. Males had a median income of $37,025 versus $27,993 for females. The per capita income for the county was $16,856. About 12.6% of families and 15.80% of the population were below the poverty line, including 20.6% of those under age 18 and 8.4% of those age 65 or over.

The San Bernardino County Sheriff provides court protection, jail administration, and coroner services for all of San Bernardino County. It provides police patrol, detective, and marshal services for the unincorporated areas of the county.

San Bernardino County is a county in which candidates from both major political parties have won in recent elections. Democrat Hillary Clinton carried the county by a majority and by double digits in 2016. The Democratic Party also carried the county in 2008 and 2012, when Barack Obama won majorities of the county's votes, and in 1992 and 1996, when Bill Clinton won pluralities. Republican George W. Bush took the county in 2000 by a plurality and in 2004 by a majority. The county is split between heavily Latino, middle-class, and Democratic areas and more wealthy conservative areas. The heavily Latino cities of Ontario and San Bernardino went for John Kerry in 2004, but with a relatively low voter turnout. In 2006, San Bernardino's population exceeded 201,000, and in 2004, only 42,520 votes were cast in the city; in 2006, strongly Republican Rancho Cucamonga had over 145,000 residents, of whom 53,054 voted.

According to the California Secretary of State, as of May 2009, there were 806,589 registered voters in San Bernardino County. Of those, 324,857 (40.28%) were registered Democrats, 306,203 (37.96%) were registered Republicans, with the remainder belonging to minor political parties or declining to state.[32]

On November 4, 2008, San Bernardino County voted 67% for Proposition 8, which amended the California Constitution to ban same-sex marriages.[33]

The current district attorney is Jason Anderson, who was elected in March 2018 and took office on January 1, 2019.

The county's primary law enforcement agency is the San Bernardino County Sheriff's Department. The department provides law enforcement services in the unincorporated areas of the county and in 14 contract cities, operates the county jail system, provides marshal services in the county superior courts, and has numerous other divisions to serve the residents of the county.

Sergeant Phil Brown of the San Bernardino County Sheriff's Department has said that gangs are growing more violent in the farthest reaches of the county, including the High Desert. Racial tensions among Chicano gangs and African-American gangs have increased dramatically in the Inland Empire, affecting even the most rural areas. "It's getting out in more remote areas," Brown said. "They go gang against gang. There's more gang violence to the general public and it's becoming more random..."[34]

The county operates the San Bernardino County Consolidated Fire District (commonly known as the San Bernardino County Fire Department). The department provides "all-risk" fire, rescue, and emergency medical services to all unincorporated areas in the county except for several areas served by independent fire protection districts, and several cities that chose to contract with the department.

The San Bernardino County Library System consists of 33 branches across the county. The library system also has inter-library loan partnerships with libraries in College of the Desert, Moreno Valley, Murrieta, and Victorville.[37] Library services offered vary from branch to branch, but include internet access, children's story times, adult literacy services, book clubs, classes, and special events.[38] The library system also offers e-books, digital music and movie downloads, free access to online learning through Lynda.com, and many other digital services.[39]

City-sponsored public libraries also exist in San Bernardino County, including A. K. Smiley Public Library in Redlands, California, which was built in 1898.[40] Other public libraries in the County include: The San Bernardino City Public Library System, Rancho Cucamonga Public Library, Upland Public Library, Colton City Library, and the Ontario City Library.[41] These libraries are separate from the county system and do not share circulation privileges.

San Bernardino International Airport is being remodeled and is expected to serve the region as an international airport. The airport will have access through interstate I-215 and I-10 through Mill Street. Terminal construction recently finished, and commercial flights are planned, awaiting carriers to select SBD as a destination city.

According to county spokesman David Wert, only 15% of the county is actually controlled by the county; the rest is cities and federal and state land. However, the county says it will make sure employment centers and housing are near transportation corridors to reduce traffic and do more to promote compact development and mass transit. The county budgeted $325,000 to fight the lawsuit.[43]

The state and the county reached a settlement in August 2007.[44] The county agreed to amend its general plan to include a Greenhouse Gas Emissions Reduction Plan, including an emissions inventory and reduction targets.